Many hand-operated trowels have been utilized for gardening in the past in which a blade is symmetrically displaced to either side of the tool center line. This spade-type trowel is provided with a handle which defines the longitudinal center line of rotation of the trowel blade, such that upon insertion into the earth around a plant, the blade is rotated by virtue of gripping the handle and rotating the handle with one's fingers which in turn rotates the blade. This trowel configuration is counter productive in the sense that rotation of the trowel slices through the earth as opposed to loosening.
Moreover, the problem associated with such a trowel having a handle which is coaxial with the longitudinal center line of blade rotation is that for arthritic or physically-impaired people, gripping the handle with enough finger force to permit the blade to both pierce the earth and be turned is difficult if not impossible. This is because the handle slips in the users hand, especially for compacted earth. What this means is that older generations of gardeners are incapable of gardening due to the lack of provision of a tool which permits ready insertion and rotation of a blade into compacted, hard earth.
More particularly, upon insertion of such a prior-art blade into the earth, rotation of the blade is difficult due to the gripping force required. The difficulty arises due to the fact that there is no lever arm upon which to permit the individual to rotate the blade with another part of his hand, rather than his fingers, thereby precluding use by severely handicapped or arthritic persons.
Another problem with a blade symmetrically disposed about the rotation axis of the tool is that upon rotation of the blade handle, while the leading edge may be rotated upwardly to cut into the earth, the trailing edge must be pushed downwardly. Since the trailing edge does not have a cutting edge at all, this results in undue force being required to rotate the tool once inserted into the earth.
In summary, the prior-art trowels which have symmetrically arranged blades about the turning axis are difficult to utilize both from the point of insertion into the earth in a digging operation as well as loosening by twisting.
While there are gardening trowels with a curved handle, the curve is not of such a nature as to permit substantial thrust to be provided by the heel of the hand during insertion, or enough of a lever arm to be used by the side of the hand during a loosening operation in which the trowel is to be rotated.